SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ce155447cee9fb2f0363d4d2b390087625694774f43b9b813fcb4e0f17a1562' 
  AND token = 'x7t37CBihvN9NtlrLVxNYzVOemqwUlCShB2iHILDKAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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