SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f8542e3c5644d2932ba9dc5e966f6653679388ee6fb44fffcbd76061096e00fc' 
  AND token = 'R8MzwvnmAR3GDQvRajTh/xP1FYHfDlBO/Q1xOfKqDcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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