SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4996128bdea9391e8a31981d77e3bffd2524d992026c690fa9f351a31135b151' 
  AND token = 'l/q/mt0aR1++diUgwIDn/jF2SRCqJ5yiThdZR/YjRSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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