SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20ae7a8ead69452f5962c6236dc88e8b27bdd156b4d3874292502fda0312ddbb' 
  AND token = '+mBcCmoZA1IJ6IbisrWEXZAEKdim3fhfWrZlEm/VbzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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