SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '777e0f03fb13e0806144369e968e5346eae39722a75aee6d90e93d244acba09d' 
  AND token = 'DFbNGXLd0y++eFNQZnvqXsU1EsQK9Af99V9eOXztzVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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