SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '198ab659da176a01743ed906674bbbe91014942094af36ba0cd3eb3b60b24a94' 
  AND token = 'McqyhjZNP45kVCVqMBfAH3ct/+ASXI3LIviigHoAm3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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