SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0043890aba66b3ba27f41958012653e1298c2a6302371356cb6d185b938048ef' 
  AND token = 'MUTKVxjjPYmZS6J+4jEwU3nvtsbLvXoX3GytCHdGA78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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