SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fa8573880ad6a68e57580524bc178c8c3e2d9024575cfb307e0da79da3c975a' 
  AND token = '4xNMcsVgCos6PuW5mAv/GRFu0lIvU/ZghBtyUmn2Xmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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