SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77c81917f5d5a4959ab2a8d54ee6f413a9e22d2114e6b378bd894806aaf1ddf6' 
  AND token = '6XShUj8K8ivgButmNq7ll+UXSjE16sij64SXgdq+ULY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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