SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28fe10ffa09aa494f81a63317b3350debe801a10194388f63dc403636dba8565' 
  AND token = 'yjcKNXwvlFCEhyEDOidzUpeTIxyVQR+k9G/r4S07Tf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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