SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3b8c9274ede6b19f3f71953b1bc64834f9c2a72e3f2737ce1dbd912109a45464' 
  AND token = 'lr0+toqJ8H5vOXkNWbE69QVA17OyPhnDyNq0WheZrjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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