SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec6de6da045e9597243d562800e3380027458d733f6df020cbf13a9162a98b1b' 
  AND token = 'lBU1dWjZvmovZtmIZnkYyzP8LwwRbp4dS73ZNEnMy3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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