SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15493d5bf7e73c53ca81c9981a8fbe436b76ec2346d51446c60ae32c6d5cf4ab' 
  AND token = 'Bo5Xvx1Ogoir9mxPSWhLVNmiGlCvpXAE2/5W+Bc8nZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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