SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5647f199f65d593d9268f63595e7c91137889309f71d5974425abf2944cf8342' 
  AND token = 'VJ+Dpt7XeU2pB8LNPeFM35CCRebwiz1gBWgFlBqVWRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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