SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '03fd039ea05cae5e3a7ca2376f8c3910f550b0fcdcccd74d802ed7a70c56e8c9' 
  AND token = 'rfOo/7jNSfp4g/Qvss5ii9ibEXBrhZzGDYbKZyvvjBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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