SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc606fec5de447028de3f89a7e763cabc3a7d61b9ae7ee7b7db4c54d9feeec29' 
  AND token = '6vSWw2bMmetVeN7oBhfIJU+7XNNlYkCpjojepiaoY5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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