SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '73b952196afef67f668e366ef8e4ef8bdeeb9d1fc7d780d8bd94cb321a7b7d48' 
  AND token = 'qq81sdFehW/SPADeB5rLdnHOPwOPp6hBJ2aNmj3g1h0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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