SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35d28d76bd640f0a1d8e23c137ab1017dc3d015aa8533ca948dbde48f239f465' 
  AND token = 'pDCeSmK1swFYV3CfDRbOrXTJnQHsEJRuxLWRm76nQLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}