SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73ec5b52d92307638df9d82fe84c1d562a094f81692b6a4bf716409d757f4677' 
  AND token = 'W5gCEAVUlBPG63snq0lGKJPbi88dRrN5T7ffjxq/xAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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