SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd543941a42986e2e616e99bbecd39fa39106a0c674d6bd251354b68db9a399db' 
  AND token = 'b/dphMqOJhQzy6jI6cZdTj6LGOBXwVgxrQzRj6jyO4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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