SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'f2a6976d45f1f5e257172a4933c30ee16f12885e45b612b27626a597196a8be1' 
  AND token = 'RmztS089ktCShSRKZm8MhWBu704lSwmnfaTqzAwUdCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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