SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51fd41b7b9c1c1c7824e7891ef3bc837eb86198243ee45b5c7fe5cbada084ff9' 
  AND token = 'r7sf8giZPOi63BkUWW5uHGKHN3CkHtCGJXo9wQnfOzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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