SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f51f241caa883880fd127741833fa57f7b43e0e0891e96f2197459c194eed155' 
  AND token = 'x75SGOptWVVGivJjTZAL5o+/M5yGzUOHKh8pIhghU9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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