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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8e6ef6dfb5cd619a4adfa2f694cf5ea5bf1f85e6fccb398756c07590e186de1' 
  AND token = 'vJ2rRMc3bgK5QZX1zaiqz7w466WGfUqby8MuqHz5pmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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