SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dd8a098033ab436a117b789bbb4f2cb53bb20f807590274feffc5eec48c5791' 
  AND token = 'HnJrNfer2sv3ebJ3P0EY4gA0SI/yPEFeezeXebmnL/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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