SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1428128e728ab6b21b90880f721cfcae56665632448fe64160dfe7895792e498' 
  AND token = 'jEuppYtcsbZUzclMx+8FveD36hV+oamr6/ufA/SHBOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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