SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '629164be670eead1d78809cf59425ab0f6e76ddbc406e3d653ff68a7e127ed0d' 
  AND token = 'j2cb0FZpqyTZkkL4EVOhqyisV9HcV4mbyspWBek19uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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