SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3da577f8251758875d162ef840b8ccf253bb32b6854650d070fe5453032e5dc' 
  AND token = 'd2Nk5KjChLFpt95ca0tgywhPlBSqSWOh8ghvHhk9eaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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