SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29db75f268b673417ee09205633f7ac07d92bd87d04bbf2ebc43674453edb90e' 
  AND token = 'QH0S0ZoRh7tykayEmEZ13JFhOKzSLTcj7YCZXJ9xdWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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