SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f74388719348aa8052e553985698a2023be644d6722c74728e530058b7a7e2d' 
  AND token = 'HimaCZXv80rO4YjdKSIAgkVJq0kAR02aZnQ/vUcFhkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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