SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3de82938a693bcadbe8617bb9d88f15f4003a4d6c7b733d4c430d90ed490896' 
  AND token = 'rcl0Rg17ODKEkyjSh1o82/5TgUqOTStvumzpH2GbPRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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