SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '137a27fc08491e4554c6a481fd2df5a99c6d638f15d0e9cb49b3f98de95edd4d' 
  AND token = 'PA4VZ6E4R7JGz19nXPKBSHJvUvlL9ZMYso2+DgVh7uM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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