SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5309a788dbecbd12653296ae22363813ab025f638c37794cd25ae0d175b637e' 
  AND token = 'IIZWkPyBT/RM5ABUeM4Q3MQebSYwHWsTaOCfidaAICQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}