SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f07c4bdcf428663abb88dbda59387c22200f9bde3064c8b20dea2ead47ea067' 
  AND token = 'ADYUI3HF4HkfDH3gwRyjsDpSLGnSkj0+5ldQOq7OiXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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