SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14726b2c49021dedbc8aeb3badb9b3888415030bce0a0b5249ebd562eec49aa9' 
  AND token = 'KHkKrjcsWzxwQVD3T1tSZAT7brDFYQiFZHr3nwnhMKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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