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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83f7f6cf5461dbcb1d03e824e761cd54d4a1e2f46b9c488a2cd6014d1c0e01e6' 
  AND token = 'z9d3kid9ktRYBw46L2r+gRs3zVVRQAN6RGWRH8xfL+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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