SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f197625f880cf47036b6aeb6fa998794df8ee4d48d207be30f04e15e1856b24c' 
  AND token = 'msZH9dyPGp/Q1lubb1j6CTXPsCkdFaiOgZFCuUM+Jww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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