SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79216dde10e4cf3388519f6ba397e42138a2b771ab014e6adbd3ed45a08edca7' 
  AND token = 'akz/bUdt/Ej+Kr7R5s8PCaDZfXdfrOFJhEyVGsvSjVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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