SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '453e7b138b24ec97c411608d3a577bc151287300a7b90a6731fde50cac7e4125' 
  AND token = '1QGEMVVoxSP81SyzCVSwe121EZU2HN/eaiw6qq27Usg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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