SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '677b019af6a25237054ce161b5163a40a69d77c188e00ea2c098439fa1fbef30' 
  AND token = '6M9tCpwroYs+kQXgI31e9FIHd1kjsi+r68/gL9kzkJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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