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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cff5bdf6417842b54db30a1bffcd24ba4b9601b9be2e2d2d46aff7844fd3a50c' 
  AND token = 'BoPlDckXn+nHpLmq7qqcJVKj7tJedfxvBqIYryRx8As=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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