SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c80bae5219b5cec31bcb56dbcecfd3bc521d475d29b99fe256d4451120a4a4e2' 
  AND token = 'grnOrmeIez9jSZLP127OpmE5k+SRb624BCyxTQwwviw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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