SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c784c921d8c732231c4a7404771a658e96496d99d2069f904cf3a835ebf14684' 
  AND token = '+3kkqQZZ2yg2H3NsjIs6KhG3O1LQYrSwQVpgBlXSFGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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