SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2901414d06e473c6909334891ee7131d747854b2468d86098dd42a946bdf2fb6' 
  AND token = '7v6SZ2lRzdCm/upUlTXgV5SoXFIy4D+WCR2GjrHSixQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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