SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aac59912ee125718a3cac22592faba9ef88cd6257716232d82b515226e7b439a' 
  AND token = 'JH9/RR/x/MdpHtjYpGlR3aVcHg619JU+Q5U8KGuftSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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