SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '128794c0367d9cf7a9481fcd4eb6ffacfe3d8432073dba776b9d49ee24b3d49f' 
  AND token = 'RR8BVBOcLlSpEnf+Z9CLSOxg3wsszG0EX5/hoLvNnrs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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