SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5909d93d99f7668218fbc02edff29bec4ee2708386fd585355efc42cdeeb6c8' 
  AND token = '1OFqotjgLrM/aLu0JCKr+HmhLDj+cBOE1+uMrIK/e7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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