SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c486340793d910ddcafdd77531e3a6f29df1f67e6745401bd263dc7c66b80c1' 
  AND token = 'lUW4sNIAQAECiCzNPxCk6MaBde9Mr+CE8NpfzBSAkvg=' 
  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"
    }
  }
}