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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a253bfe3f1b2b7e07dc11ae0d8cb64847a6143b88a0983f02816b73047e7ce2' 
  AND token = '78Wi976Yg1JRloWwyDExzwTbI0xQ9/9+MOSHhVuw2Bw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}