SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ba4e6bd127070265dcac8cf8d997243b4ccc59c1efdf80a947bdd919b0a0444f' 
  AND token = 'l/2pfmHALzjWytDvbj7AverDKOnKQXAb5KJPklwB9wY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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