SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb3c178a99d177c197f5aae15e995252ddf08c044589b3bc170dd9a3733f644e' 
  AND token = 'rteJnSnDQrY6k+7ZDr4u3Blq4R3bRSfd0LImxENQtYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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