SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3f649f251f47dadcee0465b7c5002e922f262c5985d3fd48c731745d74ac90c1' 
  AND token = 'm6D0eHZgk9xCpL9JBz+29ZBL+9n7MqzD+ei/8MQ3e7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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