SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f20b37466966276e310e8e111119e25c9513887f71401cde6f7651fd8cefe2f0' 
  AND token = 'CZ2i5B+qWthEjuQl4GXzzRaJ70lGiJZObpItsYxQMbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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