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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '514306d84684110970eb887469f030937b9254d9e29d1e1c1db3781bee6dbd94' 
  AND token = 'VCZQyg687gb+WbJ+3DDj7TMfq2pRjLSJBQfcAev29wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}