SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '749b5acc92eb3b976e3645d8dfce364a2213baff3fcaf4899413ee8ac10bbbfa' 
  AND token = 'kDgH0YviUxKe2xuPP9nfqzcPcAiiHLSzu4WNLtG3mVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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