SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48e5c15014050919be2675b5d7b5b6695f842a2c590558ae36b6d7425ba4b2b3' 
  AND token = 'gSxs/X3qIY0CFLflTOzZOktYdT0cNEtmWXEnGzItOcw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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