SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6c184ee022b16b7a498f9dd6b819fe3d1087e8ea27a23caf894208d472be06f' 
  AND token = 'KkMYrDCKGpAhrJ1igTOuYbW+UanBasnUSZzdI2QnbT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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