SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '239202f13b30234f13eaab15198f0e4bd538d5cc131a6b423548040c665f2c02' 
  AND token = 'TWF5OLYfAqjRaA8416ubYTzGQuWKLI1uSEa4qE7kKKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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