SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c90b4b71fa0aee9876fc8976168719d8794867b51d05194221f15982680b306a' 
  AND token = 'Rysxh9CRezUcz+fNPwSHAfaU8FJhZ0V+SPVGnLvjSuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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