SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8aeb78eb3e1747815de51fd090ad376c0241f44a77a2d0278013fbc859daa3f0' 
  AND token = '1azwhWavTaY2YFqssgeNVdS3Ge5XzmOOLfeEryZDnHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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