SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5dc934bf11bab5bb796a0d828cac475ef78361ea04ba24000f8491de2523ad8' 
  AND token = 'aKZ1r92ptB0zvoE797NHgp/fe4pbPHcRMnTFaOAfdjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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