SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f9574721e7f4dd7c52f68415cfd083e435dff49a42a4e8766e47c8902dc8171' 
  AND token = 'hD2azkDtmgm8coAikeaDFwkXDziRf9lMIcjCEXV+Do8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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