SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b321395632343a757705d02e1f562ea3d9812390e58a90820284b62358bbf945' 
  AND token = 'NS17TyNW9zmjVSw9pIiX+4tMEa2EUzKShM00oHfIP8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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