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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df7c949c034c78f14b040916f3b31e60151344c754c2d3252be788c2710346f2' 
  AND token = '4MQO1m7VyvYTALsTx4ev9/KQQlyZRs4xi/guFoiHM18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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