SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f04c75335bbc9b05eb2e6f1e84c4c7926750b2f3365497daf0689d12deaf298b' 
  AND token = 'MxdMYeEsJ+9gL09QwD66FNWvt12GabI4zMBOPFppTJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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