SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73a71c762deb8ccc0c339212dc46642d9b769ae101e9899d615389a06b558a32' 
  AND token = 'b/S1324MCh6236yKImd3tzWLbNUe0VGxPyvCqQ5SJbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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